The present invention relates to a thin semiconductor device, and especially a highly reliable IC card which has flexibility.
Conventional thin semiconductor devices, e.g., IC cards, are disclosed on pages 603 to 605 of xe2x80x9cElectronics, Information and Communication Handbookxe2x80x9d (second issue of the first edition, published on Apr. 30, 1990), edited by a corporation of the institute of electronics, information and communication engineers, printed by OHM Corporation and disclosed in Japanese Patent Publication No. Hei 7-99267.
FIG. 31 shows a sectional structure of a conventional contact-type IC card chip module. Bonding pads 3131 formed on a module substrate 3136 are connected to external terminals of a semiconductor chip 3134 through bonding wires 3132. These components are molded with a molding resin 3133. The bonding pads 3131 are connected through via holes 3137 formed in the module substrate 3136, which is a hard substrate, to contact electrodes 3135, which are for output and input of signals to and from the exterior and for the supply of electric power to an IC card.
FIG. 34 shows a process for manufacturing an IC card which includes the IC card chip module shown in FIG. 31. The manufacturing process comprises an upper-side photoresist films forming step for patterning the bonding pads 3131, etc. on an upper side of the module substrate 3136, a lower-side photoresist films forming step for patterning the contact electrodes 3135, etc., a conductive film etching step using a photoresist film as a mask, a step of forming via holes 3137 in the module substrate (a glass epoxy substrate) 3136, a step of plating the interior of each via hole 3137, a step of cutting a plurality of semiconductor chips 3134 (pellets), formed separately on a semiconductor wafer, a step of bonding each of the thus-cut semiconductor chips 3134 onto the module substrate 3136, a step of bonding the electrode on the semiconductor chip and the bonding pads 3131 with each other through wires 3132, a step of molding the semiconductor chip and bonding pads with resin to afford a molded chip (completion of an IC chip module), a step of milling a card substrate for mounting the molded chip thereon to form a recess, a step of applying an adhesive to the milled recess, and a step of bonding the molded chip into the recess.
FIG. 6 is a sectional view of a conventional non-contact type IC card. As shown in the same figure, a semiconductor chip 62 and the ceramic capacitors 61 and 64 are mounted on a hard substrate 66. These are connected together through bonding wires and are molded with an epoxy resin 63. The ceramic capacitor 64 is connected to a winding coil 67, which is for output and input of signals and for the reception of energy. These components are mounted between two overcoating substrates 65, which are softer than the substrate 66.
FIG. 41 is a sectional view of an IC card in which a thin capacitor chip 4151 and a thin IC chip 4153 are mounted on a neutral surface. External terminals of the thin capacitor chip 4151 and the thin IC chip 4153 are connected, using an electrically conductive adhesive, to electrodes 4155, 4157, and 4158, which are screen-printed on a flexible substrate 4156. Further, spacers 4154 and 4159 are disposed in regions where the thin capacitor chip and the thin IC chip are not present, and an upper cover 4152 is provided opposedly to the substrate 4156 so as to cover those components.
In fabricating IC cards with the structures shown in FIGS. 6 and 31, certain problems arise. For example, the manufacturing process becomes long and the manufacturing cost increases, as explained above with reference to FIG. 34. A further problem is involved therein such that the IC chip is as thick as several hundred microns and cracks upon the imposition of a bending stress thereon. A structure is known in which a reinforcing member is provided for the prevention of cracking against a bending stress. However, since this structure is for the prevention of bending, the reinforcing member used is thick and the IC card itself cannot be made thinner than 0.76 mm or so.
The IC card of the structure shown in FIG. 41 is advantageous in that the manufacturing cost is low, and that the card is highly resistive to a bending stress because a thin IC chip is disposed on the neutral surface. However, it was found out for the first time by the inventor in the present case that the thin capacitor chip and the thin IC chip were easily broken under the action of a local compressive force (point pressure) with a ball-point pen or a pencil, and that the use of the IC card is limited.
It is an object of the present invention to provide a semiconductor chip-mounted card having a structure which permits a reduction in the manufacturing cost of semiconductor devices having various thicknesses.
It is another object of the present invention to provide a semiconductor device using the above semiconductor chip-mounted card.
It is a further object of the present invention to provide a highly reliable, card-like semiconductor device having an IC chip which is difficult to break even under a local pressure (point pressure), particularly a local pressure applied to a region not larger than 1 mm2.
It is another object of the present invention to provide a highly reliable, non-contact type IC card.
It is a still further object of the present invention to provide a highly reliable multi-function IC card which is easy to use.
The above objects are achieved by a card-like semiconductor device having a thin, flexible IC chip which is 0.1 to 110 microns in thickness, wherein a reinforcing plate harder than a card substrate is provided on at least one side of the IC chip for reinforcement against a local stress. Since a local stress to be imposed on the IC chip is dispersed by the reinforcing plate, the IC chip becomes difficult to break.
For the reinforcing plate a metallic or resinous plate may be used. The use of a metallic plate permits the formation of a thinner film than in the use of a resinous plate. A suitable thickness of the reinforcing plate is in the range of 1 to 110 microns. With such a degree of thickness, the reinforcing plate can be bent following a bending stress. The reinforcing plate may be provided on both sides of the IC chip.
A semiconductor device of a higher reliability can be obtained by using a shade film which intercepts light (electromagnetic wave) traveling to the IC chip.
For the shade film, a conductive paste may be used. The shade film can be formed simultaneously with the formation of the electrode or coil by printing onto a card substrate using a conductive paste. By selecting a suitable material, the reinforcing plate can be used as a shade film.
By using a master IC chip and a plurality of slave IC chips, a semiconductor device of a higher reliability can be obtained. The master and slave IC chips are connected with each other. The master IC chip has the function of exchanging data with the exterior, while the plural slave IC chips have the function of storing data of the same contents and issuing an xe2x80x9cabnormalxe2x80x9d signal upon the destruction of any chip. Even in the event of the destruction of any of the slave IC chips, it is possible to read out the stored data.
Printed coil may be formed on one side or both sides of the card substrate. It may be formed on only one side in the case of being used in close proximity to the IC card reader. By forming coils on both sides of the card substrate, it becomes possible to detect a weaker radio wave.
The use of an IC chip having a plastic resin-coated surface permits a further improvement of reliability. As a result, a stress onto the IC chip surface induced by conductive particles can be relaxed when external terminals of the IC chip are connected to substrate electrodes through an anisotropic conductive adhesive or film.
By using an IC chip with projection-like bumps formed at the portions of the connecting terminals, a further improvement of reliability can be attained.
In the case where an IC chip is disposed between the first and second substrates, if spacers having apertures are disposed in the IC chip region and between the first and second substrates, it is possible to further improve the reliability. With such spacers, even when a stress is applied in the thickness direction of the IC card, it is possible to diminish the stress on the IC chip. In the case of a thin IC chip (50 microns or less), the spacers may be omitted.
By connecting the external terminals of an IC chip with the printed electrodes formed on a substrate through an anisotropic conducive film, a less expensive and highly reliable semiconductor device can be provided.
In the case of a semiconductor device which is an IC card, by providing external terminals on the card, a thin (300 microns or less) contact type IC card can be provided. With a coil also provided, there is provided a multi-purpose IC card for both contact and non-contact use.
Mounting an IC chip within a magnetic card permits application to uses for various purposes.
By disposing an IC chip within a displacement of 30% or less of the thickness of a card-like semiconductor device from the position of a neutral surface of the semiconductor device, a semiconductor device which is practical in point of cost and reliability can be provided.
By using an IC chip which is easier to bend than the constituent substrate of a semiconductor device, it is possible to further improve the reliability.
By forming a plurality of holes in a peripheral portion of an IC chip, there can be provided a contact type IC card.
By using a once-write type memory as a memory provided within an IC chip, it is possible to provide an economical and safe semiconductor device. This is because the use of a once-write type memory permits a reduction of the memory cell area to about half of that of E2PROM, and further, because re-write is impossible.
In a semiconductor device wherein printed electrode patterns formed on a surface of a first substrate are face-down bonded opposedly to external terminals of an IC chip, and a second substrate is disposed so as to cover the printed electrode patterns on the first substrate and also cover an upper surface of the IC chip, if a hole is formed in part of the second substrate, and another substrate having electrodes on both the surface and back thereof is embedded into the said hole, a semiconductor device superior in both economy and reliability can be provided.
If an IC chip and an IC card or an IC card controlling device are electrically connected to a capacitor chip of a large capacitance, there can be provided a highly reliable IC card without the loss of the storing and controlling function of the IC chip, even if the supply of an electric energy to the IC chip is interrupted irregularly.
In case of a card-like semiconductor device to be applied to a use which is not premised on the card being carried by man, such as a tag, or applied to a use in which a local stress is not imposed on the IC chip, it is not always necessary to use the reinforcing plate.
By using the reinforcing plate according to the present invention, a highly reliable card-like semiconductor device which is highly resistive to a point pressure can be provided, even in the case of a thin IC card having a thickness of about 100 to 250 microns. By printing coil patterns on both sides of a substrate, it is possible to reduce the area occupied by the coil. By using a shade film having electric conductivity, it is possible to prevent a malfunction of a thin IC card caused by light, ultraviolet rays, or static electricity. In the case of a proximity type IC card, it suffices to form a coil pattern on one side, whereby an IC card can be provided at low cost. By providing a thin IC chip on a neutral surface using a printed coil and an anisotropic conductive adhesive, it is possible to provide a less expensive, contact type IC card. Further, by forming a polyimide film on a chip surface, an IC card can be fabricated in a high yield.
The card-like semiconductor device according to the present invention is employable not only as a member""s card or an employee card, but also as a tag to be attached to goods, electronic money, licenses, telephone cards, railroad tickets, gift certificates, book-cards, or amusement park tickets.